Flip Gradle plugin kotlin_module names

Now common SourceSet output will have '_common' suffix, while all
variants will have the same name - '<module-name>.kotlin_module'.

This change is required for KSP as short-term workaround, as they
are using some internal properties/methods, which was mangled before
this change and hard to access in different variants.

^KT-52138 Fixed

buildSrc/src/main/kotlin/GradleCommon.kt

@@ -128,6 +128,14 @@ fun Project.createGradleCommonSourceSet(): SourceSet {
         }
     }
 
+    // Common outputs will also produce '${project.name}.kotlin_module' file, so we need to avoid
+    // files clash
+    tasks.named<KotlinCompile>("compile${commonSourceSet.name.capitalize()}Kotlin") {
+        kotlinOptions {
+            moduleName = "${this@createGradleCommonSourceSet.name}_${commonSourceSet.name}"
+        }
+    }
+
     return commonSourceSet
 }
 
@@ -205,19 +213,6 @@ fun Project.wireGradleVariantToCommonGradleVariant(
         getByName(wireSourceSet.name).associateWith(getByName(commonSourceSet.name))
     }
 
-    // Common outputs will also produce '${project.name}.kotlin_module' file, so we need to avoid
-    // files clash
-    val compileTaskName = if (wireSourceSet.name == SourceSet.MAIN_SOURCE_SET_NAME) {
-        "compileKotlin"
-    } else {
-        "compile${wireSourceSet.name.capitalize()}Kotlin"
-    }
-    tasks.named<KotlinCompile>(compileTaskName) {
-        kotlinOptions {
-            moduleName = "${this@wireGradleVariantToCommonGradleVariant.name}_${wireSourceSet.name}"
-        }
-    }
-
     configurations[wireSourceSet.apiConfigurationName].extendsFrom(
         configurations[commonSourceSet.apiConfigurationName]
     )
@@ -403,6 +398,13 @@ fun Project.createGradlePluginVariant(
         }
     }
 
+    // KT-52138: Make module name the same for all variants, so KSP could access internal methods/properties
+    tasks.named<KotlinCompile>("compile${variantSourceSet.name.capitalize()}Kotlin") {
+        kotlinOptions {
+            moduleName = this@createGradlePluginVariant.name
+        }
+    }
+
     dependencies {
         variantSourceSet.compileOnlyConfigurationName(kotlinStdlib())
         variantSourceSet.compileOnlyConfigurationName("dev.gradleplugins:gradle-api:${variant.gradleApiVersion}")

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/UpToDateIT.kt

@@ -100,7 +100,7 @@ class UpToDateIT : KGPBaseTest() {
         val originalPaths get() = originalCompilerCp.map { it.replace("\\", "/") }.joinToString(", ") { "'$it'" }
 
         override fun initProject(project: TestProject) = with(project) {
-            val pluginSuffix = "kotlin_gradle_plugin"
+            val pluginSuffix = "kotlin_gradle_plugin_common"
             buildGradle.appendText(
                 "\nafterEvaluate { println 'compiler_cp=' + compileKotlin.getDefaultCompilerClasspath\$$pluginSuffix().toList() }"
             )